Effective electron loss rates in the lower D region during the decay of solar X-ray flare events

The ionization changes that occur during solar X-ray (SXR) flares have been used to study electron loss rates at low altitudes in the D region. The electron production from SXR radiation was calculated from fluxes obtained by SOLRAD 9, and the changes in the ionization densities were measured by the partial-reflection technique. Effective loss rates were determined at various heights during the SXR flare effect and for several sizes of flares at different times of the year. The rate values obtained were lower than those reported by Reid [1970], and are interpreted as resulting from a destruction of large water cluster ions during the initial stages of the SXR flare effect. These cluster ions have fairly large effective loss rates, and their disappearance would result in a reduced effective loss rate.